1. Field of the Invention
This invention relates to novel textile treating compositions. More particularly, this invention relates to textile treating compositions comprising a new hydrophilic polyurethane. This invention further relates to a process of treating textile materials to improve the stain release and anti-soil redeposition especially of textile articles containing polyester fibers.
2. Description of the Prior Art
It is in fact known that fabrics containing a significant proportion of polyester fibers have a tendency to be hydrophobic and oleophilic. These characteristics enable greasy stains deposited on the fabric to become fixed thereto, which makes them difficult to remove. Another well-known-disadvantage of polyester fibers is that during laundering the soil present in the wash liquor can re-deposit on the fabric. One of the means of dealing with the redeposition phenomenon and of facilitating the removal of greasy stains is to deposit on the fiber a finish which imparts to them some hydrophilic character. Therefore, while the oleophilic characteristics of the fiber permit oil and grime to be readily embedded therein, the hydrophilic properties of the fiber prevent water from entering the fiber to remove contaminants therefrom. Attempts have been made to reduce the oleophilic characteristics of these synthetic fibers by coating the fibers with a coating that is oleophobic, i.e., will hinder the attachment of soil or oily materials to the fibers. Many polymer systems have been proposed which are capable of forming a film around the fibers that constitute the textile material, particularly acid emulsion polymers prepared from organic acids having reactive points of unsaturation. These treating polymers are known as soil-release agents.
The term "soil-release" in accordance with the present invention refers to the ability of the fabric to be washed or otherwise treated to remove soil and/or oily materials that have come into contact with the fabric. The present invention does not wholly prevent the attachment of soil or oily materials to the fabric, but hinders such attachment and renders the heretofore uncleanable fabric now susceptible to a successful cleaning operation. While the theory of operation is still somewhat of a mystery, soiled, treated fabric when immersed in detergent-containing wash water experiences an agglomeration of oil at the surface. These globules of oil are then removed from the fabric and rise to the surface of the wash water. This phenomenon takes place in the home washer during continued agitation, but the same effect has been observed even under static conditions. In other words, a strip of polyester/cotton fabric treated with a dilute solution of the composition of the present invention and soiled with crude oil, when simply immersed in a detergent solution will lose the oil even without agitation.
Concentrated solutions of soil-release polymers have been padded onto fabrics by textile manufacturers to impart a permanent soil-release finish to the fabric. As the amount of soil-release polymer on the fabric is increased, the ability of the fabric to release soil is increased. However, fabrics with this permanent soil-release finish possess many disadvantages. As the amount of soil-release polymer on the fabric is increased the fabric has a tendency to become stiffer and lose the desirable hand characteristic of the fabric. Thus, the upper limit on the amount of soil-release polymer to be used is determined by economics and the resulting adverse effect on the fabric. Fabrics with a heavy application of soil-release polymer do not have the same desirable appearance and hand as the same fabrics without the soil-release coating. Furthermore, practically speaking, there is a set range of soil-release agent that can be applied, dictated by commercial success.
Some soil-release polymers are effective fabric treating agents even at very low levels on the fabric, at which levels the appearance and hand of the fabric are not adversely affected. Thus, an ideal method of treating a synthetic fiber containing fabric would be to reapply a very small amount of soil-release polymer to the fabric each time the fabric is washed.